The present invention relates generally to an electronic apparatus, and more particularly to a lock/unlock unit of a foldable housing of the electronic apparatus. The “electronic apparatus,” as used herein, intends to cover, for example, a laptop personal computer (“PC”), a personal digital assistant (“PDA”), an electronic dictionary, electronic stationery, and a game machine. The present invention is suitable, for example, for a lock/unlock unit (simply referred to as a “lock unit” hereinafter”) used for the laptop PC.
Due to the recent spreads of PCs, laptop PCs are increasingly required to be easier to use. The typical laptop PC's housing includes a display unit (upper housing) equipped with a liquid crystal display (“LCD”) screen, and a body (lower housing) over which the display unit is foldable and from which the display unit is unfoldable. The display unit typically has a hook and an operation member, and the body has an engagement hole. In folding the housing, the display unit is rotated toward the body, and the housing is locked in the folded state when the hook is engaged with the body through the engagement hole. In unfolding the housing, the operation member is operated to move the hook and to release the lock, and then the display unit is rotated in a direction separating from the body. Due to the recent widespread uses of PCs to watch TV broadcasting and DVD movies, many users enjoy images on a high-quality, wide display screen, a smaller lock unit to secure the LCD screen space has been increasingly demanded.
FIG. 21 shows the conventional lock unit 10 in a lock state. The lock unit 10 includes an operation button 12 provided on a display unit 11, a hook 13 coupled with the operation button 12, a forcing member 14, such as a compression spring, provided in the display unit 11, and an engagement hole 16 provided in the body 15. The forcing member 14 forces the operation button 12 and the hook 13 in the A direction. Therefore, the hook 13 is engaged with the body 15 once inserted into the engagement hole 16. As a result, the display unit 11 is locked up on the body 15. In this state, when the operation button 12 is pressed, the operation button 12 moves with the hook 13 in the B direction and the hook 13 is disengaged from the body 15. As a result, the display unit 11 is unlocked and becomes unfoldable. Thereafter, a user opens the display unit 11 by at least a predetermined angle while pressing the operation button 12. As a result, the hook 13 is spaced from the engagement hole 16. Once the hook 13 escapes from the engagement hole 16, the user continues to push the operation button 12 upwardly or holds the top of the display unit 11 to rotate it upwardly, unfolding the display unit 11 from the body 15.
FIG. 22 shows another example of the conventional lock unit 20. The lock unit 20 includes an operation button 22 provided on a display unit 21, a hook 23 fixed onto the operation button 22, a forcing member 24, such as a compression spring, provided on the display unit 21, and an engagement hole 26 provided in the body 25. The forcing member 24 forces the operation button 22 and the hook 23 in a C direction. Therefore, the hook 23 is engaged with the body 25 once inserted into the engagement hole 26. As a result, the display unit 21 is locked onto the body 25. In this state, when the operation button 22 with the hook 23 is slid in a D direction, the hook 23 is disengaged from the body 25 and the display unit 21 is unlocked and becomes unfoldable. Thereafter, a user opens the display unit 21 by at least a predetermined angle while pressing the operation button 22. As a result, the hook 23 is spaced from the engagement hole 26. Once the hook 23 escapes from the engagement hole 26, the user continues to push the operation button 22 upwardly or holds the top of the display unit 21 to rotate it upwardly, unfolding the display unit 21 from the body 25.
The conventional lock units 10 and 20 for the laptop PC are not so easy to use. Firstly, the lock unit 10 requires a width of each of the display unit 11 and the body 15 to secure a moving range of the hook 13 or the length of the engagement hole 16, and prevents an effective utilization of the housing space. As a result, demands for a miniaturization of the entire apparatus and a wide screen display unit cannot be met unfavorably. The lock unit 20 solves this problem but the unfolding direction of the display unit 21 is perpendicular to the D direction in which the operation button 22 is moved. Therefore, in unfolding the folded housing, the user needs to execute two actions, such as a movement of the operation button 22 in the lateral direction, and then an upward rotation of the display unit, deteriorating the operability.